The present invention relates to a portable telephone set tracking connection system for tracking movement of a portable telephone set in a mobile communication network constituted by a plurality of switching units.
In general, a mobile communication network of this type is constituted by a plurality of switching units. When a portable telephone set as a moving object moves from one area being managed by a certain switching unit to an adjacent area being managed by another switching unit, the switching unit which manages the area to which the portable telephone set has moved receives a movement notification signal from the portable telephone set.
In this case, the switching unit for managing the area to which the portable telephone set has moved (this unit will be referred to as a visitor location switching unit hereinafter) notifies the switching unit for managing the area from which the portable telephone set has moved (this unit will be referred to as a home location switching unit hereinafter) of the movement of the portable telephone set. Subsequently, the home location switching unit sets the identification data of the visitor location switching unit in the home location register of the home location switching unit. In addition, the home location switching unit transfers information (set in other areas in the home location register) such as the called number of the portable telephone set from which the movement notification has been received to the visitor location register in the visitor location switching unit, thereby performing tracking connection in a calling operation with respect to the portable telephone set which has moved from the area of the home location switching unit to the area of the visitor location switching unit.
Assume that calling processing is to be performed with respect to a portable telephone set which has moved from the area managed by a home location switching unit to the area managed by a visitor location switching unit. In this case, in a conventional portable telephone set tracking connection system in a mobile communication network, since the portable telephone set must transmit a signal notifying the movement to the area of the visitor location switching unit, the processing performed by the portable telephone set is complicated. In addition, location registers must be installed in the respective switching units, and information associated with a portable telephone set which has moved must be transmitted between the home location switching unit and the visitor location switching unit. As a result, the arrangement of the mobile communication network is complicated.